A distributed repeater for repeating a terrestrial digital television broadcast signal and a distributed repeating method thereof will be described as exemplary embodiments, but the present invention is not limited thereto.
For a broadcasting service, main transmitters and repeaters are placed according to peripheral topography/natural features on the earth, and a broadcasting zone of a broadcaster. The repeater is installed in an area where a broadcast signal of a low level is received from the main transmitter in order to prevent poor signal reception and broaden the signal transmission coverage of the main transmitter.
FIG. 1 illustrates one example explaining a broadcasting service employing general repeaters using respectively different frequencies.
Referring to FIG. 1, in a broadcasting service employing general repeaters, a main transmitter 101 sends out broadcast signals using a transmission frequency, and other repeaters 102 to 105 repeat the broadcast signals using frequencies B, C, D and E, respectively, which are different from the transmission frequency A. The repeaters 102 to 105 use respectively different frequencies B, C, D and E to overcome poor signal reception or broaden a broadcasting coverage. Since the repeaters 102 to 105 use a plurality of frequency bands, many frequency resources are required, which makes the frequency use significantly inefficient.
If the repeaters use the same frequency as the main transmitter for a broadcasting service, an effect of reusing a frequency can be obtained even in a local area, improving frequency utility efficiency.
FIG. 2 illustrates another example explaining a broadcasting service employing general repeaters, which are on-channel repeaters that use an identical frequency.
A main transmitter 201 sends out broadcast signals using a transmission frequency A, and each of on-channel repeaters 202 to 205 repeats signals, using the same frequency as the transmission frequency A. To this end, a receiver must be able to identify output signals of the main transmitter 201 from those of the on-channel repeaters 202 to 205 although they use the same frequency band. Also, output signals of the on-channel repeaters 202 to 205 must be identical to the output signal of the main transmitter 201, and time delay of the two output signals must be short.
However, the on-channel repeating technology has the following limitations of low utilization of existing emission facilities and large investment. Therefore, there is a need for a cost-effective technology that can maximize the use of the existing emission facilities, allow implementation thereof within a short time, and improve the frequency utility efficiency.
FIG. 3 illustrates another example for explaining a broadcasting service using general repeaters, which are distributed repeaters using the same frequency but different from a frequency of a main repeater.
A main transmitter 301 sends broadcast signals using a transmission frequency A, and distributed repeaters 302 to 305 repeat the signals using a frequency B different from the transmission frequency A.
Referring to FIG. 3, as the distributed repeaters are used, output power of the distributed repeater is not affected by feedback signals which are generated by low isolation of Tx/Rx antennas because transmitting frequency is different from receiving frequency. That is, the existing emission can be used to a maximum extent, and implementation thereof can be achieved within a short time, so that a cost-effective broadcasting service network can be implemented. To this end, a receiver must be able to identify signals sent from the distributed repeaters 302 to 305, and output signals of the distributed repeaters 302 to 305 must be the same.
Therefore, it is required to develop a distributed repeater that outputs the same output signals as output signals of other distributed repeaters and removes noise and multipath signals so that characteristics of the output signals of the distributed repeater becomes superior to those of the input signals.